In the case of electrical space heaters it is well known to control their energization so as to vary their power inversely with the temperature measured at some location within their environment. This mode of regulation, serving to maintain the temperature of the heated space at a substantially constant level, is generally more satisfactory than the usual thermostatic control according to which a heater is turned off when the temperature exceeds the upper limit of a selected range and is turned on again when it drops beneath the lower range limit. Such an on/off control, moreover, is particularly uneconomical in the case of a catalytic gas burner which is known to operate with reduced efficiency upon start-up after cooling and which, accordingly, ought to be supplied during such a start-up phase with fuel at an increased rate. This conventional mode of operation therefore practically prevents the utilization of such burners in industrial plants, hothouses or the like.
In my copending application Ser. No. 372,053, filed Apr. 26, 1982, I have disclosed a system for the control of a catalytic gas burner wherein a flow regulator enables the gas supply to be adjusted manually or automatically in response to changing temperatures. Since, however, proper combustion always requires a certain minimum supply rate, this regulator can reduce the heating effect only to a limited extent. If, for example, the space heated by such a burner experiences an increase in temperature due to incident sunlight, the regulator will not be able to reduce the power of the heater sufficiently to compensate for that temperature rise.